Type of Delivery Does Not Affect How a Baby's Microbiome Is Developed, Study Finds

The theory that babies' gut microbiome development is affected based on how they are born, whether it be vaginally or by cesarean, is a theory no more. According to a recent study published in Frontiers in Cellular and Infection Microbiology, researchers report the way a baby is born does not determine how their microbiome is developed.

The gut microbiome serves a number of immunological and metabolic functions to the body linked to infant development. Many studies have implicated type of delivery as a major factor in the development of the early infant gut microbiome. For example, one small study from 2010 documented an abundance of vaginal genera in infants born vaginally, while infants delivered by caesarean section exhibited stool microbiomes dominated by skin commensals.

More recent, larger studies have not identified vaginal microbes as key members of early infant gut microbiome, and differences between vaginally and cesarean-delivered infants remain to be found.

In this cohort study of 621 Canadian pregnant women and their newborn infants, researchers investigated this long-time assumption that has resulted in inconsistent data collected in past studies. For more clear results, researchers collected and evaluated pre-delivery maternal vaginal swabs and infant stool samples at 10-days and 3-months of life.

After evaluating the effects of maternal vaginal microbiome composition and other variables on the development of infant stool microbiome's, it was found the infant stool microbiomes showed significant differences in composition by delivery at 10-days postpartum. However, this effect could not be explained by maternal vaginal microbiome composition and was reduced by 3 months, according to the study.

The mothers' vaginal microbiome composition did not predict the composition of babies' stool microbiome at 10 days or three months, the researchers found.

Regardless of birth type, no evident patterns in microbiome development from mother to baby were found.

The study indicates the transfer of vaginal bacteria to the infant gut is limited and the maternal vaginal microbiome is not a large contributor to developing a baby's gut after birth.

After examining maternal vaginal microbiome effects, researchers also attempted test the use of intrapartum antibiotics. Researchers said antibiotic use did not counter the finding that the maternal vaginal microbiome is not predictive of infant stool microbiome composition.

Researchers are now testing the breast milk microbiome, also.

The similarities in data between birth type and maternal vaginal microbiome composition, as well as the use of antibiotics implies that delivery mode alone does not account for differences between infant stool microbiomes.

Study authors mention they could not draw conclusions about maternal stool microbiome's influence because they did not collect stool samples from the women in the study.